title: A novel centromere monospecific serum to a human autoepitope on the histone H3-like protein CENP-A.
abstract: Centromere autoantibodies are commonly found in the serum of patients with some systemic autoimmune diseases. Previous studies have shown that a major human centromere autoantigen is the histone H3-like protein CENP-A. Although the human cDNA has been cloned, native CENP-A has been neither isolated nor expressed in Escherichia coli, and specific antibodies to this chromatin-associated centromere protein are not available yet. In this report, a highly charged peptide on CENP-A (residues 3-17) was used to generate a monospecific antibody that reacts by immunoblots with the 17 kDa centromeric protein. Immunofluorescence analysis showed reactivity of this anti-CENP-A serum in several but not all mammalian culture cells analyzed, suggesting that the sequence of this histone-like centromere protein could be more variable throughout evolution than originally thought. Selective extractions of human placenta nuclear proteins and immunoblot analysis indicated that CENP-A behaves in a similar way to the core histone polypeptides after nuclease digestion of chromatin. Also, immunoblot analysis demonstrated that the CENP-A peptide used as immunogen is a target region on the CENP-A molecule in several but not all CREST patients analyzed with high titers of autoantibodies to the centromere. Lastly, we found that in Jurkat cells induced to apoptosis, CENP-A remains associated with the centromere, in contrast to other human autoantigens studied during apoptosis.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Cádiz, Spain. manuel.valdivia@uca.es
authors.forename: M M
authors.initials: MM
authors.lastname: Valdivia
authors.forename: J
authors.initials: J
authors.lastname: Figueroa
authors.forename: C
authors.initials: C
authors.lastname: Iglesias
authors.forename: M
authors.initials: M
authors.lastname: Ortíz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology* / Q000378:metabolism; D001324:Autoantigens / Q000276:immunology; D001327:Autoimmune Diseases / Q000276:immunology; D002503:Centromere / Q000737:chemistry* / Q000276:immunology; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry* / Q000276:immunology; D000939:Epitopes / Q000276:immunology / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells / Q000166:cytology; D006801:Humans; D015151:Immunoblotting; D019169:Jurkat Cells / Q000166:cytology; D008322:Mammals; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism; D010920:Placenta / Q000737:chemistry
chemical_list: D000906:Antibodies; D001324:Autoantigens; C000619700:CENPA protein, human; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone; D000939:Epitopes; D010446:Peptide Fragments